Preprints  

The marine reservoir age (MRA) that is the difference between the ¹⁴C age of the ocean and that of the atmosphere at a given time. In geochronology, knowing the local MRA is important to derive accurate calibrated ages for ¹⁴C-dated marine material. However, MRA values for coastal West Africa are scarce. From the ¹⁴C-dating of know-age bivalves from Museum collections, we calculated MRA values and populated the MRA dataset for coastal West Africa over a latitdinal transect from 33° N to 15° S.

The carbonate wall deposits of the Trou du Renard Cave (France) were dated using a multimethod approach: U-Th dating by bulk dissolution of samples and ICPMS, U-Th dating by laser ablation ICPMS imaging and radiocarbon dating. The sample compositions were studied to ensure that they can give reliable ages. Ages ranging from 187.9 ± 5.3 ka and 1.4 ± 0.1 ka were found. This approach should make it possible to establish more robust chronologies of archaeological caves.

Radiocarbon dating is a widely used tool to establish chronologies for sediment records. We show that modern aquatic plants in the Laguna del Peinado lake system (Altiplano-Puna Plateau) give too old ages caused by reservoir effects from the input of old groundwater and volcanic CO₂. Our results reveal a spatial variability of the modern reservoir effect within the lake basin, which has implications for radiocarbon-based chronologies in paleoclimate studies in this region and similar settings.

The U–Th–He method is a technique to determine the cooling history of minerals. Traditional approaches to U–Th–He dating are time consuming and require handling strong acids and radioactive solutions. This paper presents an alternative approach in which samples are irradiated with protons and subsequently analysed by laser ablation mass spectrometry. Unlike previous in-situ U–Th–He dating attempts, the new method does not require any absolute concentration measurements of U, Th, or He.

Here, we present the lighting setting implemented in the new Luminescence Dating Research Laboratory at Stony Brook University, USA. First, we performed spectral measurements on different light sources and filters. Then, we measured the loss of signal in quartz and feldspar samples when exposed to various light sources and durations. Finally, our lighting setting is suitable for a luminescence darkroom laboratory, it is simple, inexpensive to build, and durable.

Open data has become the modern science meme. Funding bodies and publishers support open data. However, the open data mandate frequently encounters technical obstacles, such as a lack of a suitable data format for data sharing and long-term data preservation. Such issues are often community-specific and demand community-tailored solutions. We proposed a new human-readable data format for data exchange and long-term data preservation of luminescence data based called XLUM.

Cosmogenic nuclides like ¹⁰Be are rare isotopes created in rocks exposed at the Earth’s surface and can be used to understand glacier histories and landscape evolution. ¹⁰Be is usually measured in the mineral quartz. Here, we show that ¹⁰Be can be reliably measured in the mineral pyroxene. We use the measurements to determine exposure ages and understand landscape processes in rocks from Antarctica that do not have quartz, expanding the use of this method to new rock types.

Accurately dating ocean cores is challenging because the radiocarbon age of water masses vary substantially. We identify ash fragments from eruptions >4000 km from their source and use these time-markers to develop a new age-depth model for an ocean core in, Placentia Bay, North Atlantic. Our results show that the radiocarbon age of waters masses in the Bay varied substantially during the last 10,000 years and highlight the potential of using ultra-distal ash deposits in this region.

The Wasserstein distance is shown to be an appropriate dissimilarity metric for comparing distributional data such as detrital mineral ages. Using synthetic and real data we compare the Wasserstein distance to the commonly used Kolmogorov-Smirnov distance. The results are, in general, similar, but where they differ the Wasserstein distance is found to have more geologically sensible results. Code required to calculate the Wasserstein distance between distributions is provided in python and R.

Volcanic ash layers are a common tool to synchronize records of past climate, and their estimated age relies on external dating methods. Here, we show that the chemical composition of the well-known, 12000 year-old Vedde Ash is indistinguishable with several other ash layers in Iceland that are ~1000 years younger. Therefore, chemical composition alone cannot be used to identify the Vedde Ash in sedimentary records.

(U-Th)/He dating relies on proper characterization of apatite crystal dimensions so that eU concentrations and dates can be calculated accurately and precisely, but there is systematic error and uncertainty on geometric measurements. By comparing 2D microscopy to “true” 3D measurements, we present a simple solution to correcting the error and quantifying the geometric uncertainty on eU and dates. Including this geometric correction and uncertainty matters for data evaluation and interpretation.

We report aspartic and glutamic acid racemization analyses on Neogloboquadrina pachyderma and Cibicidoides wuellerstorfi from the Arctic Ocean (AO). The rates of racemization in the species are compared. Calibrating the rate of racemization in C. wuellerstorfi for the past 400 ka allows the estimation of sample ages from the central AO. Estimated ages are older than existing age assignments (as previously observed for N. pachyderma), confirming that differences are not due to taxonomic effects.

The Great Unconformity represents an enormous amount of time lost from the sedimentary record. Its origin is debated, in part, due to different approaches used to interpret zircon (U–Th)/He ages. This thermochronometric system is ideal for this problem because the temperature sensitivity varies according to radiation damage. Here we explore the uncertainty associated with the radiation damage model and show how this limits our ability to resolve the origin of the Great Unconformity.

When using the uranium-lead radiometric dating method on very young materials (e.g. Quaternary age zircon and carbonate minerals), it is important to accurately account for the production and decay of intermediate ‘daughter’ isotopes in the U-series decay chain. DQPB is open-source software that allows users to easily make such corrections for a variety of sample types and to produce publication-ready graphical outputs of the resulting age information.

We present our model ChronoLorica. We coupled the original Lorica model, that simulates soil and landscape evolution, with a geochronological module that traces cosmogenic nuclide inventories and particle ages through the simulations. These properties are often measured in the field to determine rates of landscape change. The coupling enables calibration of the model and study how soil, landscapes and the geochronometers change under complex boundary conditions such as intensive land management.

Acid leaching is commonly used to remove damaged portions of zircon crystals prior to U-Pb dating. However, a basic understanding of the microstructural processes that occur during leaching is lacking. We present the first 3D view of zircon dissolution based on X-ray computed tomography data acquired before and after acid leaching. These data are paired with images of etched grain surfaces and Raman spectral data. We also reveal exciting opportunities for imaging radiation damage zoning in 3D.

We proposed a new non-destructive mineralogical methodology on inframilimetric grains that allows to quantify the hematite and goethite content and hematite/goethite ratio of grains prior to (U-Th)/He geochronological analysis. (U-Th)/He data performed on different aliquots with different acquisition time shows no remarkable differences in age, opening a new way to investigate the (U-Th)/He data evolution in supergene lateritic duricrusts.

This paper outlines a method that helps mineral explore for gold. When can see the alteration caused by the mineralising fluids, it is possible to use geochemical methods to vector towards the deposit. But such methods failed at Martabe. We decided to work out why. Our results showed that there were several distinct and separate very short-lived alteration events. The answer might be that vectoring is possible only when samples are compared from the same mineralising system.

Paleomagnetic data from Cascade Lake (Brooks Range, Alaska) extend the radiometric-based age model of the sedimentary sequence extending back 21 kyr. Correlated ages based on prominent features in paleomagnetic secular variations (PSV) diverge from the radiometric ages in the upper 1.6 m, by up to about 2000 years at around 4 ka. Four late Holocene cryptotephra in this section support the PSV chronology and suggest the influence of hard water or aged organic material.

Prehistoric volcanic eruptions are often dated by wiggle matching series of radiocarbon ages on tree rings to standard calibration curves, ignoring potential contamination by 'old' carbon given off by the volcano. We modeled the effects of low amounts of contamination on wiggle match dates for the 10th century Changbaishan eruption and found evidence of contamination in all. We propose a new protocol to identify the presence of contamination, and provide more secure dates for major eruptions.

The timing and duration of fluid activity within a gold deposit enables a greater understanding of how the deposit evolved and thus help future mineral exploration. This research uses high resolution dating methods to unravel the overprinting fluid activity at the Martabe gold field in Sumatra. Methods outline in this report can be applied to deposits globally.

Potassium-based geochronology, including the ⁴⁰Ar/³⁹Ar and K-Ar methods, provides critical constraints on the timing and duration of many events and processes in earth history. These methods assume that a key parameter, the fraction of potassium with a mass of 40, does not vary in some relevant materials. Some recent work has identified some variability in these materials. This work examines the effects of this variability on calculated K-Ar and ⁴⁰Ar/³⁹Ar ages.